The invention relates to an aerodynamic wing, comprising an upper deck extending in operation in a longitudinal direction and in a transversal direction; wherein the upper deck is shaped and arranged to produce a vertical lifting force which is oriented perpendicular to the longitudinal and the transversal direction when the aerodynamic wing is exposed to a wind flow in a direction oriented parallel to the longitudinal direction; wherein a plurality of ribs are connected to the upper deck, said ribs lying in a plane parallel to the direction of the vertical lifting force and the direction of the wind flow; the aerodynamic wing being coupled to a base platform arranged below the wing in service via a plurality of fastening lines.
Aerodynamic wings of the aforementioned design are adapted to form an aerodynamic profile in operation. Such aerodynamic wings according to the prior art are often provided with flexible upper and lower decks to allow folding and compacting of the wing for storing purposes. In operation, the aerodynamic wing is expanded to its aerodynamic profile design having a convex curvature of the upper deck and a concave curvature of the lower deck thus effecting an uplift force when exposed to a flow of air stream in a direction substantially parallel to the upper and lower deck. The uplift force is generated by a low pressure acting onto the upper deck and a high pressure acting onto the lower deck. The uplift force effects a pulling force onto the base platform. The base platform may be a stationary arrangement, which is e.g. adapted to transform the pulling force and a resulting veering out of one or more pulling cables connecting the base platform to the wing into another form of energy like electrical energy. Preferably, the base platform is a non-stationary arrangement like a watercraft, e.g. a person standing on a kiteboard or a commercial ship.
Often, in such aerodynamic wings one or more openings are provided in the front side of the wing to allow ram air to enter the wing inner space and to thus stabilize the aerodynamic wing profile.
A plurality of ribs serve to connect the upper and lower deck and to maintain a substantially constant distance between the upper and lower deck along the aerodynamic wing, namely to establish an aerodynamic profile of the wing. Usually, such ribs may be manufactured from a textile material to allow folding and compacting of the wing.
Further, such ribs are used for accommodating the line attachment points which are required to couple the aerodynamic wing to fastening lines coupling the wing to a base platform, a steering unit or the like to transfer the uplift force via the fastening lines.
Usually, each rib is oriented in a plane parallel to the direction of the vertical lifting force acting in the region of the rib and the direction of the wind flow at said region. Such rib will be oriented perpendicular to the upper and lower deck. However, diagonal ribs extending in an oblique but not perpendicular direction with respect to the upper and the lower deck may be provided. It is to be understood that the aerodynamic wing may have an overall curvature thus resulting in locally different directions of the lifting force whereby the sum of the lifting forces result in a direction and a magnitude of an overall lifting force. The above discussed orientations of the ribs refer to the respective local orientation of the decks.
Usually, the fastening lines are secured to the upper and lower deck via fastening points at the ribs. In particular in large scale aerodynamic wings forces of significant magnitude must be transferred via such fastening points. To provide operational safety, the ribs must provide high strength properties and still further may need reinforcement patches in the region of the fastening point. However, such high strength properties and reinforcement patches result in increased weight of the aerodynamic wing thus adversely affecting the efficiency of the aerodynamic wing.
Still further, it is known to increase the number of fastening lines to thus reduce the level of local stresses at the fastening points of each fastening line. However, such high number of fastening lines result in increased weight of the aerodynamic wing and its fastening lines thus also adversely affecting efficiency of the wing.